1. Field of the Invention
The present invention relates to a method for producing hollow carbon nanocapsules, and more particularly to a method for producing high purity hollow carbon nanocapsules.
2. Background of the Invention
A hollow carbon nanocapsule is a polyhedral carbon cluster constituted by multiple graphite layers having a balls-within-a ball structure. The diameter of a hollow carbon nanocapsule is about 3–60 nm. Hollow carbon nanocapsules have special fullerene structure and optoelectronic properties and can be utilized in various fields such as medicine (medical grade active carbon), light and heat absorption, electromagnetic shielding, organic light emitting materials, solar energy receivers, catalysts, sensors, carbon electrodes in lithium batteries, nanoscale composite materials with thermal conductivity and special electrical properties, and nanoscale carbon powder for printing.
However, a process for producing high purity carbon nanocapsules has not yet been described in conventional literature. Only a trace amount of hollow carbon nanocapsules has been found when producing carbon nanotubes. Moreover, by conventional process, the main product is long carbon nanotubes, and there is a strong van der Waals force between carbon nanocapsules and carbon nanotubes. Therefore, it is not easy to isolate carbon nanocapsules. The related application on carbon nanocapsules is limited and insufficient.
U.S. Pat. No. 6,063,243 discloses a process for producing carbon nanotubes as a main product with a nanoparticle byproduct. This patent uses direct current to conduct an arc discharge reaction.
German Patent No. 19740389 uses a laser beam evaporated catalytic process to produce carbon nanofibers, carbon nanoparticles, and fullerene. The process has high cost and low yield, and the product is not easy to purify.